This application is the national phase under 35 U.S.C. xc2xa7 371 of PCT International Application No. PCT/DE00/03296 which has an International filing date of Sep. 21, 2000, which designated the United States of America, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention generally relates to a contactor arrangement having two contactors and a blocking element. In one aspect, the contactors include guides for contact supports, with a blocking element being deflected from an intermediate position to a blocking position by the guide of the operated contactor when one of the contactors is operated. The blocking position may prevent operation of the unoperated contactor. Further, the guide of the unoperated contactor may act in an operating region on the blocking element if an attempt is made to operate the unoperated contactor. In addition, the guides may act directly on the blocking element.
2. Background of the Invention
Contactor arrangements are known, for example, from DE 195 48 480 C1 or DE 24 40 361 A1.
EP 0 313 954 A1 discloses a contactor arrangement having two contactors and a blocking element. The contactors have guides for contact supports. The blocking element is deflected from an intermediate position to a blocking position by the guide of the operated contactor when one of the contactors is operated. The blocking position prevents operation of the unoperated contactor. The guide of the unoperated contactor acts in an operating region on the blocking element if an attempt is made to operate the unoperated contactor. The guides act directly on the blocking element via pins.
Electrical loads are often connected to a supply network in different ways. One example of such types of connection is the optional connection of a load in star or delta to a three-phase network or to a reversing circuit, in which either the polarity of the DC voltage is reversed or a three-phase network is connected to a load alternatively with a positive phase sequence and a negative phase sequence.
The electrical load is generally connected to the supply network via contactors. If both contactors were operated at the same time, this would result in a short between the phases. Such simultaneous operation of both contactors must therefore be prevented. In known arrangements, this is achieved by the contactor arrangements that have been mentioned.
It repeated attempts are made to operate the unoperated contactor, fatigue occurs over the course of time in the blocking elements mentioned previously. Finally, they break, so that they can no longer carry out their function.
In the contactor arrangement according to EP 0 313 954 A1, the blocking element is coupled to the movement of the contact supports via pins, which are inserted at the side into the contact support guide. The movement of the contact supports is thus transmitted to the blocking element via the pins. When the blocking element is in the blocking position, then the movement of the contact support is blocked via the pin. This likewise prevents the unoperated contactor from being operated. In practice, it has been found that the high forces that occur result in the pins breaking off. The pins thus represent a weakness in this contactor arrangement.
An object of an embodiment of the present invention is to provide a contactor arrangement in which the guides act directly on the blocking element, and in which no fatigue nevertheless occurs in the blocking element.
Such an object may be achieved wherein essentially only compression forces occur in the blocking element as a result of any attempt to operate it.
An embodiment of the invention is based on the knowledge that fatigue in the blocking elements or the pins is caused by tensile and/or bending stresses. If the stress is essentially purely compressive, on the other hand, virtually no material fatigue occurs.
An essentially purely compressive stress can be produced particularly easily if, when an attempt to operate it is made, the blocking element is pressed underneath the operating region against at least one stop, so that the blocking element is supported on the at least one stop during the attempt to operate it.
If, in addition, essentially only compression forces occur, in the guide of the unoperated contactor when an attempt is made to operate it, virtually no material fatigue occurs in the guide of the unoperated contactor, either.
The contactor arrangement has a particularly simple design if side surfaces of the contactors face one another, the blocking element is arranged in a blocking element holder, and the blocking element holder is arranged between the contactors.
The creation of essentially only compression forces in the guide of the unoperated contactor can be achieved, in design terms, particularly easily if the blocking element can pivot in a pivoting plane which runs at right angles to the side surfaces.
The mechanical design becomes even simpler if the guides act on the blocking element in an operating direction, and the operating direction runs parallel to the side surfaces.
If the blocking element holder is arranged at least partially i in the contactors, the contactor arrangement occupies only a small amount of space. The occupied space is a minimum when the side surfaces are adjacent to one another.
If the contactors each have one front face and one rear face, which is opposite the front face, and the rear faces and the blocking element holder end flush with one another, this necessarily results in the blocking element being positioned in a defined manner. There is no longer any need for adjustments.
If the blocking element is in the form of a rotating cardioid, the blocking element operates particularly reliably.
In principle, the contactors may be of any desired configuration. Generally, however, at least three load contacts can respectively be operated via the contact supports.